电缆绝缘老化的高压频域介电谱诊断评估方法

High Voltage FDS Diagnosis and Evaluation Method for Cable Insulation Aging

通过检测不同阶段的整体/局部热老化XLPE电缆高压介电谱,探究不同老化程度和不同局部老化段与完好电缆占比对高压介电谱的影响。结合XLPE材料老化过程中的理化特性和机械特性变化,分析宏观高压介电与微观物理化学性质的关系,并探讨基于高压频域介电谱的XLPE电缆老化评估方法。结果表明:具有一定程度老化的电缆,无论是整体老化还是局部老化,其高压介电谱都会呈现分层的特征,这是由于热老化过程中材料分子断键产生的极性基团和晶区破坏导致材料极化强度增大导致的。此外,具有一定老化程度的整体热老化、局部热老化缺陷电缆试样的分层度L均大于1,L矩阵可作为电缆老化现象的评估参数;较高检测电压等级(1.0U0)介电谱曲线的非线性度η对老化程度的变化敏感,可以作为电缆老化程度的评估特征;可以结合η的数值及曲线积分数值区间判定电缆是否为局部老化。

The high voltage FDS for XLPE cables of both overall and local thermal aging in different stages are detected,and the effects of various aging degree and different local aging section proportion are explored.Besides,by combining the changes of physical and chemical properties and mechanical properties of XLPE material in the aging process,the relationships between the macroscopical high voltage dielectric and the microscopical physicochemical properties are elucidated.Finally,the aging evaluation method of XLPE cable based on high voltage FDS is discussed.The results show that the high voltage FDS of cables with a certain degree of aging,whether overall or local aging,show the characteristics of delamination,which is due to the increase of polarization intensity caused by the destruction of polar groups and crystal regions caused by molecular bond breaking.Besides,the L of cable samples with overall and local thermal aging defects with a certain aging degree is greater than 1,and the L matrix can be used as the diagnosis parameter of cable aging phenomenon;nonlinearityhat higher detection voltage level(1.0U0)is sensitive to the change of aging degree,and is less affected by the proportion of local defects,which can be used as the evaluation feature of cable aging degree.It can be determined whether the cable is partially aged by combining the value ofhand the range of integral.